The present invention relates to solar cells and in particular to solar cells having a conductive electrode pattern and bus bar interconnect which is applied to the solar cell in a single solder dipping procedure.
Photovoltaic devices such as silicon solar cells promise a viable alternative to non-replenishable fossil fuel energy generation. Light energy (photons) incident on a solar cell's surface must enter and be absorbed within the cell to be converted to an electrical current. The electrical current is carried by electrodes to bus bars which are attached to inter-connectors which join many cells together to form a solar panel. In the prior art, bus bars are sometimes directly attached to the solar cell by induction heating or other soldering means. Leads to the bus connections are also sometimes soldered directly upon the solar cell. This has the disadvantage of subjecting the solar cell to an additional heating step, and additional thermal stress. This can damage the solar cell. In contrast, the present invention attaches the bus bars by a solder dipping process and provides means for interconnecting cells without further subjecting cells to heat which can damage the solar cell. Possible cracking of the solar cell is prevented or greatly reduced. In the present invention the bus bars extend beyond the solar cell periphery and thus serve as inter-connectors to electrically connect the solar cells together, thus eliminating direct soldering upon the solar cell. In addition, the present invention also teaches a means of attaching the bus bars and making a pre-metallized grid conductive in a single solder dipping procedure.